The invention relates to a piston rod-less linear drive comprising an elongated housing having a receiving space for a drive part adapted to perform an axial movement, said drive part being kinematically coupled by way of dog extending through a longitudinal slot in the housing with a guide slide, said guide slide being movingly guided on a linear guide externally on the housing in the longitudinal direction thereof, said linear guide possessing two guide sections directed in a transverse direction laterally toward opposite longitudinal sides.
Furthermore the invention relates to the housing of a linear drive, which is more especially of the type initially mentioned, comprising a receiving space, extending in the longitudinal direction, for an axially movable drive part, and moreover a longitudinal slot rendering possible the extension therethrough of a dog kinematically coupled with the drive part, the envelope curve of the cross sectional shape of the housing being delimited at least in the longitudinal portion, which contains the longitudinal slot, of the housing, by four delimiting lines at least substantially forming a rectangle.
Such a piston rod-less linear drive with a correspondingly designed housing is disclosed in the European patent publication 0 612 377 B1. This known linear drive has housing with a rectangular outline in cross section with a receiving space containing a piston-like drive part, a radially extending through slot being provided at one point in the housing wall, such slot opening internally into the receiving space and externally into a section of the outer face of the housing.
On an adjoining external face section, running perpendicular to this, of the housing a linear guide is provided constituted by a guide rail, on which there linearly runs a guide slide, such guide slide being connected with the dog in a driving manner. The linear movement of the drive part results in a ganged, guided linear movement of the guide slide, such slide being provided on a support face with attachment means for the attachment of a load to be moved.
The known linear drive is admittedly characterized by an extremely high quality of the longitudinal guide function. Furthermore it possesses relatively compact dimensions. However extensive parts of the outer face of the housing are occupied by the linear guide and by the force coupling means present between the drive part and the guide slide so that in effect only two outer side sections of the housing of the linear drive are available for attachment or fastening purposes.
Accordingly it is one object of the present invention to provide a piston rod-less linear drive and a housing more particularly suitable therefor, in the case of which despite the compact dimensions extensive areas of the outer side of the housing may still be kept accessible.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, the invention provides a piston rod-less linear drive of the type initially mentioned in which the longitudinal slot is so arranged that its plane extends obliquely in relation to the guide plane, defined by the transverse direction and the longitudinal direction, of the linear guide, the outer of such slot opening facing the guide plane.
In connection with a housing of the type initially mentioned the object of the invention is attained even because the plane of the longitudinal slot, as viewed in the cross section of the housing, extends in such an oblique fashion that it intersects the envelope curve at an angle departing from 90 degrees.
Whereas in the case of a structural design in accordance with the said European patent publication 0 612 377 B1 the plane of the longitudinal slot extends in parallelism to the guide plane defined by the linear guide, something which means that a large area of the outer periphery of the housing is occupied, the oblique arrangement of the longitudinal slot results in there being a close association between the dog and the linear guide without this resulting in disadvantages as regards the quality of the guiding action, there furthermore being an availability of large areas of the housing""s periphery for or other fastening purposes. In this respect it is possible to arrange the linear guide and the longitudinal slot very close together.
Irrespectively of any possibly present linear guide in the case of a housing, which is normally shaped with a rectangular outline, the plane of the slot may be so aligned that it extends neither in parallelism nor at a right angle to the envelope line of the cross sectional outline of the housing and owing to such oblique arrangement there will be a favorable placement of the outer opening of the longitudinal slot, which keeps the major part of the rectangular outline of the housing available for any desired purposes.
Further advantageous developments of the invention are defined in the dependent claims.
It is convenient for the longitudinal slot to be so arranged that the plane thereof makes an acute angle with the guide plane defined by the linear guide.
In the case of a particularly compact design there is an at least partial overlap of the linear guide with the receiving space in the transverse direction of the guide plane. The dog may in this case run past the linear guide obliquely.
In the case of a further advantageous design the outline of the housing of the linear drive is characterized by an outer face, which possesses four outer face sections opposite to one another in pairs, of which one section has the linear guide and of which other sections are designed to serve as fastening or mounting faces.
The fastening faces may possess fastening means able to be relied upon for the attachment of the housing or for the attachment of additional part on the housing. In this case the longitudinal slot is preferably so shaped that it either directly opens in the outer face section of the housing having the linear guide or opens in a transitional zone between this above mentioned outer face section and one of the two fastening or attachment faces adjoining such section of the outer face section.
In the case of a housing possessing a rectangular outline it is possible for the dog to run within the envelope curve of the cross sectional outline toward the outer face section, having the linear guide, of the housing so that there are no projecting components.
The linear guide is preferably connected along its entire length directly with the housing of the linear drive, it more particularly being designed in the form of a guide rail, which is preferably secured to the housing without the use of screws. Attachment may be by means of swaging rolling operation or preferably by an integral design of the guide rail, and the housing, for example by extrusion.
The linear drive may be designed as an electrically operated unit and for instance possess a lead screw drive which is able to move a lead screw nut serving as the drive part. It is more particularly advantageous however for the design to be such that the drive part is in the form of a piston and for the actuating force to be provided by the action of a fluid. In such a case a sealing means is provided for the longitudinal slot to prevent uncontrolled loss of fluid.